The present invention relates to an optical storage apparatus using a removable medium such as an MO cartridge or the like and, more particularly, to an optical storage apparatus for efficiently adjusting a light emitting power of a laser diode to an optimum power when a medium is loaded.
Use of an optical disk as a storage medium in a multimedia has rapidly been developing in recent years. For example, in addition to conventional 3.5 MO cartridges of 128 MB and 230 MB, media of a high density recording such as MO cartridges of 540 MB and 640 MB have also been introduced in recent years. In an optical disk drive, it is important to properly set the light emitting power of a laser diode in accordance with a temperature at that time, the kind of medium, the position (zone) on the medium, and the like in order to stably perform the reading and writing operations. Generally, when a temperature is high, the necessary light emitting power is low, and when the temperature is low, the necessary light emitting power is high. The media can be divided into the kind of media having 128 MB and 230 MB and recorded by a pit position modulation (PPM), and the kink of media having 540 MB and 640 MB recorded by a pulse width modulation (PWM) in order to raise the recording density. In the PPM recording, the light emitting power is changed at each of three stages of reading, erasing, and recording. In the PWM recording, it is necessary to change the light emitting power at each of four stages of reading, erasing, first writing, and second writing. When PWM recording a medium of a direct overwrite corresponding type, since no erasing operation is executed, it is necessary to change the light emitting power at four stages of reading assisting first writing and second writing. Further, with respect to a position on a medium, a larger light emitting power is necessary on the outer circumference than that on the inner circumference.